Serena Williams is up to 23 grand slam singles titles, the latest in Melbourne while pregnant, as she revealed her bump to the world this week. Photo / Getty Images
It is tempting to wonder which sporting adversarial debate would best fit the head-to-head formula.
Sir Ian Botham and Ian Chappell, perhaps? These two cricketers loathe each other with such a passion that on one occasion they had to be prised apart in an Adelaide car park.
Or how about Roy Keane and Mick McCarthy, of whom the splenetic Irishman famously raged at a World Cup training camp: "I didn't rate you as a player, I don't rate you as a manager and I don't rate you as a person."
The most memorable debates, though, tend to be settled more by force of rhetoric than the theatre of raw belligerence. To that end, there is one duel that clearly needs staging sooner rather than later: golf commentator Peter Alliss versus tennis superstar Serena Williams.
The silver-tongued hero of the pipe-and-slippers brigade versus the sassy queen of Compton. The incorrigible old buffer who believes women are far too dainty and breakable to box - "I think women are more delicate than men" - versus the 23-time major champion who, it emerged this week, won her most recent Australian Open when she was eight weeks pregnant.
Williams routinely hits back at any attempt to bracket her by her gender, let alone an aspersion that womenfolk should reach for nothing more than subservient frailty.
Asked at Wimbledon last year about being considered "one of the greatest female athletes of all time", she replied, icily: "I prefer the words, 'One of the greatest athletes of all time'."
Alliss is 86 years old and unlikely to change his stripes. But pitch him into a battle of words with Williams and at least his words would be exposed as not merely antediluvian, but demonstrably wrong. It would do tennis a service, too, for this is a sport that, despite all its efforts at equality, perpetuates the very fallacy of female fragility that Alliss upholds.
The only reason, ultimately, that women play best of three sets at Grand Slam tournaments, as opposed to best of five, is the underlying assumption that they are too weak to last the longer distance.
Williams shows up such a notion for the rot that it is. Time and again, she has rewritten the manual on mental and physical dominance.
In 2003, her sister Yetunde was murdered in a drive-by shooting. In 2010, she split her foot open on a broken bottle in Munich. The following March, she suffered a pulmonary embolism, involving several life-threatening blood clots on her lungs. Somehow, through it all, she has amassed 72 singles titles, including 10 beyond age 30.
What cements the legend is the revelation that she secured a seventh Australian Open title, without dropping a set, while deep in the first trimester of pregnancy. These early stages can affect women to varying degrees, but at seven weeks " roughly the point at which Williams demolished fellow American Nicole Gibbs for the loss of four games " the embryo is the size of a blueberry. At eight weeks, by most guides, strong morning sickness is not uncommon. Williams' nonchalance in coming through a fortnight of gruelling Grand Slam tennis in broiling heat is, even by her standards, a momentous feat.
Brooklyn Decker, wife of former world No 1 Andy Roddick, was overwhelmed with admiration. "She won a slam pregnant?" she wrote. "I needed Andy to dress me, carry me and place me on the toilet."
Naturally, Williams has been in no mood to make a fuss. To do so would be to cut against her credo of refusing to be delineated along gender lines. Instead, she simply posted a side-on picture of her growing bump on SnapChat with the words "20 weeks", leaving her publicist to clear up any ambivalence. Some go even further, claiming that true equality dictates Serena's news should be treated no differently to that of Andy Murray, who reached a final in Melbourne two weeks before becoming a father. Perhaps so, but it is fair to say Murray did not undergo quite the same level of pre-natal upheaval.
Williams hopes, as she has always done, that her triumph reshapes the prism through which women in sport are judged, while consigning the bovine preconceptions of men like Alliss to the skip where they belong.